Alternating-current motor.



0. KN O PFLI. ALTERNATING CURRENT MOTOR. APPLICATION FILED APR. 29,1912.

Patented Aug. .3, 1915.

2 SHEE SSH EET I- Flg. 2 1

WITNESSES: fidgypiazw,

" INI/ENTOR 0. KND'PFLI.

ALTE RNATING CURRENT MOTOR. APPLICATION FILED APR.29, 1912.

Patented Aug. 3, 1915.

2 SHEETS-SHEET 2.

Fig. 5.

- ml ENTER I I A TTORNEY WITNESSES:

OTTO KNPFLI, GE ZURICH, SVTIZ'ZEP' OEIRLIKON, Q3 UERLIKGN. NE

ALTERNAZ? IN .SSSIG-NGR 3 MASSKENIER'EAT i ZURICH, W MIND.

.hpplication filed April 29. 19152.

To all 7171 10727 it may concern Be it known that l:, O'r'ro Known. itcitizen of Switzerland, residing" Zurich. Switzerland. have invented scertain new and useful ilklternatiugurrent lvlotor. which the followingis such :1 full. clear, and exact description. 2:: will enable any oneskilled in the art to which it :ipper aius to make and use the same,reference being heel to the accompanying drmviugs, forming part of thisspecification.

' The single phase commutator motor to which this invention relatesbelongs to the class of repulsion motors in "which change in thedirection of rotation is produced by changing the magnetic axis of thestator and not by changing the position of the brushes. ally anauxiliary re ersible winding displaced by about ninety (90) electrical.degrees from the main stator Winding and connected in series therewith.T he rotor hits a commuted Winding and a set of short-circuited brushesin the axis of the main stator Winding. The starting torque depends. in.such motors, upon the choice of the number of turns of the auxiliaryWinding. in operation,- these motors have a series character istic, 6.,the number of resolutions is pendent Within Wide limits upon .md andupon the position of the axis of the resultant stator megnetization Withreference to the axis of the short-eircuited brushes.

Diiierent arrangements have been p oposed in order to give these motorsa shunt operating cherracteristic, or least to prevent them from racingunder sudden decrease of load. Most of these arrangements involvechanging the connections of the motor when it has reached the desiredspeed I and this is done either by hand or by the aid of centrifugaldevices. In such machines, there are, as a rule, a. set of auxiliarybrushes disposed at an angle to the Working brushes and these auxiliarylorushes ore short-circuited when the desired speed has been reached,thus giving to the machine the characteristics of a single phaseinduction motor. These auxiliary brushes instead of being directlyshort-circuited, may be connected to the line either directly or througha transformer.

The object of this invention is to provide means for changing a singlephase com. tutor motor of the shove described a motor having: shuntcherscterittie Specification of Letters Z'Estcnt.

In such machines there is gener 27x1 a m "1 i.

merited e. sells serial No. x.

will not involve 'ny change in connections between the storming andrunning conditions and will at the some. time allow the motor develop :1large starting: torque while not causing to he iited :1 nearly synchrorrnine by the ninnber of tor and the periodicity the l I k .u ier objectis to provide an arrange ment whereby the motor will act as anelectic-dynamic broke it disconnected. ti 1 The rotor s provided with acornnn ted Winding; and with a set of short circuited Working brushes6., 7 "Whose ztxis'ap proximately coincides with the axis of theDisplaced by {96) electrical degrees from all 1.

brushes 8. 9 which are connected to the sec y Winoiug 15, of thetransformer or potential regulator 6, the primer winning 14 of thensit'ormer being connected in parallel nitn the main inducing Winding 3it part thereof. instead of having; two separate windings. thetransformer may he of the 'fx'llll] shown in Fig. 2.

To change the direction of rotation of the n'iotor. the direc u of thecurrent through the nuiin inducing winding is reversed. by means of thetwo-pole switch 10 in the motors illustrated in Figs; 9 and 3. and bythe threeoole switch 20 in the motor shown in Fig. e'. For motors whichrun at a speed ividel; differing from .ynchronism. the direction of thehi. impressed upon the exciting: brushes should preferably not hechanged when the current through the main inducing Winding: is reversed,and the switches and cqn'niectirss shown in Figs. 2', 3 and 4t are ksoarranged that changing the position of switche wil not reverse thedirection. J. l r, impressed on the exciting 5 .u the worrying brushesis a. set of exciting small part of the entire winding, as in The maininducing winding may be divided into a number of coils as illustrated inFig. 3 where 11, 12 and 13 are sub-divisions of this winding. In thismotor the current through all of the coils 11, 12 and 13 is reversed. toreverse the direction of rotation. Instead of connecting the excitingbrushes to the main inducing windingthrough a transformer, they may bedirectly connected. In F 3, these brushes are shown connected inparallel with coil 12, but they may be connected in parallel with anyone or more of the main inducing coils as desired. "When the excitingbrushes are conductively connected to the inducing winding, the motorwill act as an electro-dynamic brake when the line current is cut off.

In motors which are designed to run at approximately synchronous speedand have the stator winding divided into a number of coil groups, and inwhich the auxiliary brushes are connected to only a relatively Fig. 3,it is not absolutely necessary that the direction of the E. M. F.impressed upon the auxiliary brushes be unchanged when the direction-ofthe current in the main inducing winding is changed.

In Fix. a, a three-pole switch and a. single coil transformer having;three interconnected groups of turns 17, 18 19 are provided and theconnections are so arranged that the winding always remains conductivelyconnected to the exciting brushes but the direction of the E. M. F.impressed upon these brushes is not changed when the direction of thecurrent through the winding 3 is reversed, the group to the brushes inone position of the switch and the group 18 being connected to thebrushes in the other position of the switch. in both positions of theswitch the primary of the transformer is connected in pa 'allel with themain intuiciirc winding".

In order to increase the starting torque, it will, in some cases. be ofadvantage to impress an E. M. l. on the working brushes, and this E. M.F. may be derived from the secondary winding 16 of the transformer asillustrated in Fir. 5.

In the motors described, the magnitude of the starting torque willdepend upon the ratio of the number of the turns of the auxiliary windinm to the tur s of the main in ducing' winding, and also upon the ohmicand the inductire resistances of the circuit which includes theexciting, brushes. The speed of the motor when in operation will. dependupon the ratio of the turns off the auxiliary winding to those of themain in ducing winding, and upon the mamritude and direction. of the M.F. impressed on tie exciting brushes.

19 being: connected Having; fully described my invention, what I claimas new and desire to secure by Letters Patent of the United States is:

1. In an alternating; current motor, the combination with an inducingmember provided with a main inducing winding, and an auxiliarywinding),- connected in series therewith, of an induced member closed byway of brushes alone an axis approximately coincidin; with the axis orthe main inducing winding, means for impressing on the in. duced memberalone an axis displaced from the axis of the main inducing winding anEi'M. F. derived from said winding, and means for changing the directionof the cur rent through the main inducing winding without changing thedirection of said E. M. F. and without changing the current through theauxiliary winding.

2. In an alternating current motor, the combination with an inducingmember pro vided with a main inducin, winding and an auxiliary winding,of an induced member having working brushes in the axis of the maininducing winding and excitingbrushes displaced from the working brushes,a trans former having; three groups of intercom nected coils, one ormore of said groups being connected in parallel with the. main in ducingwinding, and means for chunccting either of two of said groups oi coilsto the exciting brushes, said. means being: adapted. to connect a ggivcnterminal groups to a different exciting, brush from that to which thecorresponding terminal of the other group is adapted to be connected.

3. In an alternating current motor, the combination with an inducingmember provided with a main inducing winding and an auxiliary winding,of an induced. member having working: brushes in the axis of the main inducin; winning and exciting brushes displaced from the working, brushes,a transformer having three. groups of intercom nccted coils, one or moreof said groups being. connected in phrallel with the main inducingwinding and one {group being connectcd to the exciting brushes, and theswitch arranged to Simultaneously reverse the direc .ion of the currentthrough the main inducing winding. disconnect one coil group from theexciting brushes and connect anotl'ier' coil group to said brushes butin reverse direction from that in which the first mentioned coil groupwas connected.

In testimony whereof, I have hereunto set niv hand and afiixed my soulin the presence ot' the twosubscribinfl witnesses.

OTTO KNQPFLI.

Viitncsses CARL Ennnnsnn, EMIL (Joxnxo REDINGER.

of one of said

